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How to choose the solenoid valve core material

First, the use of
The fluid in the tubing must match that of the media in the selected solenoid valve model. The temperature of the fluid must be less than the calibrated temperature of the selected solenoid valve. Solenoid valves allow the viscosity of the fluid to be generally below 20 EST (Celsius), and more than 20 EST should be specified. Working pressure difference, the maximum pressure difference in the pipeline is less than 0.04MPa should be used such as ZS, 2W, ZQDF, ZCM series and other direct-acting and step-by-step direct-acting; minimum operating pressure difference is greater than 0.04MPa can be used when the pilot type (pressure Differential type) Solenoid valve; the maximum working pressure difference should be less than the maximum calibration pressure of the solenoid valve; the general electromagnetic valve is one-way operation, so pay attention to whether there is back pressure difference, if there is a check valve installed. When the fluid cleanliness is not high, a filter should be installed in front of the solenoid valve. Note The influence of ambient temperature on the solenoid valve The power supply current and power consumption should be selected according to the output capacity. The power supply voltage is generally allowed to be ±10%, and attention must be paid to the VA at the time of AC start. The value is higher. The general electromagnetic valve requires better cleanliness of the medium. Pay attention to the flow aperture and the nozzle diameter; solenoid valve is generally only two-way control switch; conditions allow to install the bypass pipe, easy to repair; have water hammer phenomenon to customize the solenoid valve opening and closing time adjustment.
Second, reliability
Solenoid valves are classified into two types: normally closed and normally open; Normally selected are normally closed, energized open, and power off; however, normally open type is used when the open time is very long and closed. Life test, the factory is generally a type test project, to be exact, there is no professional standard for solenoid valves in China, so choose a solenoid valve manufacturer with care. When the operation time is very short, the direct-acting type is generally selected, and the large-caliber selection is used for the fast series.
Third, security
General solenoid valve is not waterproof, please use waterproof type when conditions do not allow, factory can be customized. The highest rated pressure of the solenoid valve must exceed the maximum pressure in the pipeline, otherwise the service life will be shortened or other unexpected situations will occur. Corrosive liquids should use the full stainless steel SLF) solenoid valve. Explosion-proof products must be selected for explosive environments. Type, strong corrosive fluid should use plastic king
Fourth, economy
There are a lot of solenoid valves that can be used in the general structure of solenoid valves, but the most economical products should be chosen based on the above three points.
One: direct-acting solenoid valve; there are two types of normally closed and normally open. Normally closed type when the power is off, when the coil is energized, electromagnetic force is generated, so that the moving core overcomes the spring force and the static iron core directly opens the valve and the medium is the passage; when the coil is powered off, the electromagnetic force disappears, and the moving iron disappears. The core is reset under the action of the spring force, and the valve port is closed directly, and the medium is blocked. Simple structure, reliable operation, normal work under zero differential pressure and micro vacuum. Normally open type is just the opposite.
Second, step-by-step direct-acting solenoid valve; The valve is used once open valve and secondary valve open in one, the main valve and the pilot valve step by step to electromagnetic force and pressure difference directly open the main valve port. When the coil is energized, an electromagnetic force is generated to cause the moving iron core and the static iron core to pull in. The pilot valve port is opened and the pilot valve port is disposed on the main valve port, and the moving iron core is connected with the main valve core. At this time, the main valve is The pressure of the chamber is unloaded through the pilot valve port, and the main valve core is moved upwards under the influence of the pressure difference and the electromagnetic force to open the main valve medium. When the coil is de-energized, the electromagnetic force disappears. At this moment, the moving iron core closes the pilot valve hole under the action of its own weight and spring force. At this moment, the medium enters the upper cavity of the main valve core in the balance hole, so that the pressure of the upper cavity rises. The main valve is closed under the action of the spring return and pressure, and the medium is shut off. Reasonable structure, reliable operation, and reliable operation at zero differential pressure.
Third, the indirect pilot solenoid valve; the series solenoid valve is formed by connecting the pilot valve and the main valve core to form a channel; the normally closed type is closed when it is not powered. When the coil is energized, the generated magnetic force causes the moving iron core and the static iron core to pull in, the pilot valve port opens, and the medium flows toward the outlet. At this time, the pressure in the upper cavity of the main valve plug decreases, which is lower than the pressure on the inlet side, forming a pressure difference against the spring. The resistance moves upwards and reaches the purpose of opening the main valve port, and the medium circulates. When the coil is de-energized, the magnetic force disappears and the moving iron core resets and closes the pilot port under the action of the spring force. At this moment, the medium flows from the balancing hole, the pressure of the upper cavity of the main valve core increases, and the downward movement of the main valve core is caused by the force of the spring. Close the main valve port. The normally open principle is just the opposite. Such as: SLA, DF (φ15 above diameter), ZCZ and so on.
Concerned about the four properties of the solenoid valve
1. Safety: 1. Corrosive medium: The plastic king solenoid valve and all stainless steel should be used; for the strongly corrosive medium, the diaphragm type must be selected. Example CD-F. Z3CF. Neutral medium, should also use copper alloy valve shell material for the solenoid valve, otherwise, the valve shell often rust off, especially infrequent occasions. Ammonia valves cannot use copper. 2. Explosive environment: must use the appropriate explosion-proof grade products, open installation or dust more occasions should use waterproof, dustproof varieties. 3. The nominal pressure of the solenoid valve should exceed the maximum working pressure in the pipe.
II. Applicability:
1. Media characteristics
1. Electromagnetic valves of different types are selected for quality gas, liquid state or mixed state respectively. Example ZQDF is used for air, ZQDF-Y is used for liquid, ZQDF-2 (or -3) is used for steam, otherwise it may cause malfunction. ZDF series multi-function solenoid valve can be connected to gas and liquid. It is best to state the media status at the time of subscription, and it is not necessary to install the user.
1.2 medium temperature products of different specifications, otherwise the coil will burn off, aging of the seals, seriously affecting life expectancy.
1.3 Medium viscosity, usually below 50 cSt. If it exceeds this value, the diameter is larger than 15mm and ZDF series multi-function solenoid valve is used for special orders. Path is less than 15mm high viscosity solenoid valve.
1.4 If the cleanliness of the medium is not high, a backflushing filter valve should be installed in front of the solenoid valve. In the case of low pressure, a straight-acting diaphragm type electromagnetic valve can be used as a CD-P.
1.5 If the medium is directional and does not allow reverse flow, ZDF-N and ZQDF-N are required to use two-way flow, please make special requirements.
1.6 The medium temperature should be selected within the allowed range of the solenoid valve.
2, pipeline parameters
2.1 Select the valve port and model according to the medium flow requirements and the pipe connection method. For example, for the switch from one pipe to two pipes, select the CA5 and Z3F for the smaller path, and select the ZDF-Z1/2 for the medium or large path. Another example is to control the convergence of two pipes, please select ZDF-Z2/1.
2.2 According to the flow and valve Kv value selected nominal diameter, but also with the pipe diameter. Please note that some manufacturers are not marked with Kv value, often the size of the valve hole is smaller than the interface diameter, must not be coveted and the price is low.
2.3 Working pressure difference The minimum operating pressure difference is 0,04 Mpa or more. Indirect pilot type is available. The minimum operating pressure difference is close to or less than zero. It must use direct-acting or step-by-step direct type.
3, environmental conditions
3.1 The maximum and minimum temperatures of the environment shall be selected within the allowable range. If there is any excess error, special orders shall be made.
3.2 When the relative humidity in the environment is high and there is water and rain and other occasions, the waterproof solenoid valve should be selected
3.3 There are often vibrations in the environment, bumps and impacts, etc. Special varieties should be selected, such as marine solenoid valves.
3.4 Use in Corrosive or Explosive Environments
3.5 If the environmental space is limited, please use the multi-function solenoid valve, because it eliminates the bypass and three manual valves and is easy to repair online.
4, power conditions
4.1 According to the type of power supply, choose AC and DC solenoid valves respectively. In general, AC power is easy to use.
4.2 Voltage specifications Use AC220V, DC24V as much as possible.
4.3 Power Supply Voltage Fluctuation Normally, AC is used for +10%, -15%, and DC is allowed to be ±10%. If there is excess error, it is necessary to adopt voltage regulation measures or make special orders.
4.4 The rated current and power consumption should be selected according to the power supply capacity. It should be noted that the value of VA is higher when the AC is started, and the indirect-conducting solenoid valve should be preferred when the capacity is insufficient.
5, control accuracy
5.1 Ordinary solenoid valve only open and close two positions, in the control of high precision and stable parameter requirements, please use a number of solenoid valve; Z3CF three normally open solenoid valve, with micro-open, fully open and close the three types of flow; ZDF ―Z1/1 combination multi-function solenoid valve has four types of full-open, wide-open, small-open and full-open.
5.2 Operation time: refers to the time when the electrical signal is turned on or off to the completion of the main valve action. Only the company's patented product multi-function solenoid valve can adjust the opening and closing time respectively, not only meeting the control precision requirements, but also preventing water hammer damage.
5.3 Leakage The leakage value given on the sample is a common economic grade. If it is too high, please make a special order.
Third, reliability:
1. Work life: This item is not included in the factory test project and it is a type test project. In order to ensure the quality should be selected from the regular manufacturers of brand-name products.
2, the work system: a long-term work system, repeated short-term work and short-term work of three. The company's conventional products are long-term work systems, that is, coils allow long-term power work. For long-term valve opening only short-term closure, you should use normally open solenoid valve. When used in a short-time work system and in large quantities, special orders can be made to reduce power consumption.
3. Operating frequency: When the operating frequency is high, the structure should be direct-acting solenoid valve, and the power supply should listen to the preferred communication.
4. Operational Reliability This test has not been formally included in China's professional standards for solenoid valves. In order to ensure the quality of this test, it is recommended to select the brand-name products of regular manufacturers. In some cases, the number of operations is not large, but the reliability requirements are very high, such as fire protection, emergency protection, etc., must not be taken lightly. Of particular importance, it should also take two consecutive double insurance.
Fourth, economy:
Non-economy is one of the criteria for the selection of funds, energy, and even the waste of life. However, it must be based on safety, application, and reliability. Economics and economics are not only the selling prices of products, but also priority should be given to their function and quality. As well as the cost of installation, maintenance and other accessories, and more importantly, the cost of a solenoid valve in the entire automatic control system in the entire automatic control system and even the production line is minimal. huge. In short, economics not only refers to the price of a product, but the ratio of the price of a product to the price of a comprehensive product. Solenoid valve failure and rectification I. After the solenoid valve is energized, I will not check whether the power supply wiring is bad → Reconnect the wiring and the connector, check whether the power supply voltage is within ± working range → Adjust the normal position range, and whether the coil is desoldering → re-welding , Coil short-circuit → Replace the line working pressure difference is not appropriate → Adjust the pressure difference → or replace the appropriate solenoid valve fluid temperature is too high → replace the electromagnetic valve with impurities so that the main spool of the solenoid valve and moving iron core stuck → proceed Cleaning, if any seal damage, replace the seal and install the filter. The viscosity of the liquid is too high. The frequency is too high and the service life is up. → Replace the product. 2. The solenoid valve cannot close the main valve core or the seal of the iron core is damaged → Replace the seal. Fluid temperature, viscosity is too high → replace the solenoid valve of the counterpart impurities into the solenoid valve valve core or moving core → cleaning, spring life has reached or deformed → replace, throttle orifice balance hole plugging → timely cleaning, working frequency Too high or have reached the end of life → Reselect product or update product III. Leak in other conditions → Check if the seal is damaged, and if the spring is badly fitted. → loose connections or leakage seal has been broken → screws or replace the noise → loosening fasteners the head, tighten the seal energized. The voltage fluctuation is not within the permissible range and the voltage is adjusted. Core suction surface impurities or uneven, timely cleaning or replacement.
The difference between solenoid valve and electric valve
1. Switch form: The solenoid valve is driven by the coil and can only be turned on or off. The switching time is short. The motor-driven valve is usually driven by a motor. The on-off operation requires a certain amount of time to be simulated and can be adjusted.
2. The nature of the work: The solenoid valve has a very small flow coefficient, and it has two working pressures. The difference is small. For example, the general 25-gauge solenoid valve has a much smaller flow coefficient than the 15-bore electric ball valve. Solenoid valves are driven by solenoids and are easily damaged by voltage surges. Equivalent to the function of the switch, that is, the opening and closing of the electric valve is generally driven by a motor, which is more resistant to voltage surges. Solenoid valves are quick-opening and fast-closing. They are generally used in small flow and small pressure, where the switching frequency is large, and the electric valve is reversed. The opening degree of the electric valve can be controlled. The state is on, off, half open and half off. It can control the flow of medium in the pipeline and the solenoid valve can not meet this requirement. Solenoid valve can be reset when the power is off. The electric valve needs such a function to add a reset device.
3. Applicable process: Solenoid valve is suitable for some special process requirements, such as leakage, special fluid medium, etc., which is more expensive. Electric valve is generally used for adjustment, but also a switch, such as: fan coil end.

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